Flexible metal tubing



June 13, 1933 I c. sfHuNGER'l-'RD `1.9135390 lFLEXIBLE METAL' TUBING Filed Dec. 23. 1931 DMEM! Figi?,

g Mmmm Patented June 13, 1933 rar @HABILES B. HNGEBFORD, F 'WATER'JIO'WN,y -CONNECTICUT, SSIGNOR T0 AMERICAN METAL HOSE COMPANY, 01E' WATERBUBY, UUNNECTICUT, A COEPURAhu TION F CONNEGTICUT ricamata Marat. inname Application tiled becernber 26 1931. aerial No. am.

rllhis invention relates to exible metal tubing, and more particularly to means for preventing the overlapping convolutions from spreading and bpening up the joint to thereby cause the tube to leak from the twisting of the tube. lt will be evident as these tubes are formed by spirally winding a strip4 off metal so that the convolutions overlap tor a portion of their width, that if the tubes are twisted in the reverse direction the overlapped convolutions begin to separate and thus permit the tube to leak. It has been known to prevent this untwisting by winding the strip on a mandrel having flat sides, as for example a hexagonal mandrel, thus producing a hexagonal tube, but these tubes apparent 'from the following description talren in connection with the accompanying drawing in which the preferred construction is illustrated, it however being understood that various modifications and changes may be employed without departing .trom the principles of the invention.

1n the accompanying drawing:

Fig. 1 is a side elevation of a section of a Hexible metal tube with my improved locking means applied thereto;

Fig. 2 is a transverse section thereof;

Fig. 3 is a view similar to Fig. 1 showing a somewhat dierent arrangement of locking means;

Fig. 4 is a longitudinal section on an en-v larged scale through several convolutions of the interlocked type of conduit;

Fig. 5 is a transverse section thereof substantially on line 5-5 of Fig. 4;

Fig. 6 is a longitudinal section through the locking means of the so-called over lapped type of conduit, the section being substantially on the line 6 of Fig. 1, but on an enlarged scale; and

17 ig. 7 is a 'transverse section substantially on line 7-7 of Fig. 6.

Referring to `lligs. 1, 2, 3, 6 and 7,`the tube 10 is shown as ormed in tne usual manner by spirally winding a strip of metal 1l so that the adjacent convolutions overlap for a portion of their Width. One. ortion of the strip indicated at 12 is o -set inwardly from the other portion 13, and the edge of the portion '12 is provided with an outwardly extending flange'14 While the free edge 13 is provided with an inwardly ex'- tending flange 15. When laid in the spiral to iorin the tube the edge of the flange 15 engages the outer portion of the portion 12 of the adjacent convolution, while the edge of the flange 14 engages the inner portion of the portion 13 of the adjacent convolution. that when the tube is straight the ilanges 14 and 15 are spaced from each other longitudinally of the tube and also from the connecting portion 16 so that as the tube is flexed laterally there is plenty of room for the flanges to slide on the surfaces of the adjacent convolutions.

llt will, however, be evident that if the tube is twisted in the opposite direction from the direction in which the convolutions are laid, then the overlapping convolutions' will tend to separate in a direction radially et the tube thus opening the joint between the adjacent convolutions and causing the tube to leak. l overcome this objection by providing co-acting' means on the adjacent overlapped convolutions which preventsthese adjacent convolutions from sliding on each other longitudinally of the convolutions, or that is, in a direction peripherally of the tube, and therefore as the tube cannot untwist, the joints between the convolutions cannot separate and cause the tube to leak.

'llhis untwisting can be prevented by scoring or indentin either inwardly or outwardly the over apping portions adjacent -the convolutions so that one of them a The convolutions are also so wound` recess or depression and the other. has a projection extending into said recess to give a sort of locking or keyed efi'ect to prevent the adjacent convolutions from sliding relative to each other in a direction longitudinally of the convolutions, or that is, in a direction periplherally of the tube.

I ave found the simplest and the most effective means for so interlocking the convolutions to be a groove indicated at 17 extending longitudinally of the tube. can be formed by rolling the roove in the surface of the tube after it is ormed, or if preferred it can be formed when the tube is being wound. On the drawing the groove is shown as being rolled inwardly from the outer surface, but it will of course be understood the same effect is secured if it is rolled outwardly from the inner surface. The groove may extend straight or parallel to the axis of the tube as indicated in Fig. 1, or it may extend s pirally of the tube as indicated in Fig. 3. groove may be used or more than one may be used if found desirable. The indentations however need not be formed by a continuous groove, but may be formed in the shape of multiple indentations formed in the tube either while it is being Wound or after it is wound. It will be seen that this groove provides an inwardly extending projection 18 in the louter convolution and at the same time bends the inner convolution to provide a recess 19 in its surface in which the extension 18 projects. 'Therefore the co-action of the two gives an interlocking or keyed effect to prevent the two sliding longitudinally on each other, but does not interfere with `lateral relative sliding movement of the overlapped convolutions. Therefore while these indentations prevent unwinding or separating of the convolutions by the untwisting of the tube, they do not interfere with the flexing of the tube in the usual manner. In Fig. 6 I have shown the space includedbetween the flanges 14 and 15 as filled with a fiber packing 20, but this can be used or omitted as desired. When used it reduces the so lcalled packed tube.

n Figs. 6 and 7 this interlocking means is shown as a plied to the so-called overlapped tube, lut is equally applicable to the so-called interlocked type of tube, as shown in Figs. 4 and 5. In this type of tube instead of having merely the free edges of the flanges engage the surfaces of the overlapped convolutions, they are folded so as to provide portions 21 and 22 extendin longitudinally of the tube which are olded over each others edges thus providing a socalled interlocked type of tube. The convolutions are formed of a strip of metal 23 wound spirally as inthe( first form with the inwardly off-set portion 24 haying the This A single longitudinall provides interlocking portions-on t e overlapped convolutions to prevent untwisting the same as in the first form, as will be evident from an inspection of Figs. 4 and 5, the laterally projecting portions 26, 27 and 28 interlockingy with corres ending grooves or recesses in adjacent wa ls of the convolutions. In both types the adjacent convolutions are overlapping.

It has been found in actual use that this construction effectively prevents twistin lof the tubes, .and therefore prevents over apping convolutions of the tubes Vfrom se arating due to this twisting operation. urthermore, this interlocking construction can be applied without greatly increasing the cost of the tube and without materially decreasing its carrying capacity. As indicated, it is applicable to the so-called overlap d type and the interlocked type of tube, an to packed and un acked tubes without reducing their fiexibility. The tubes are applicable for carrying liquids or gases, or for electrical conduits and the like.

Having thus set forth the nature of my invention, what I claim is:

1. A circular fiexible tube comprising overlapping spirally wound convolutions, and the wall of said tube being depressed to provide a longitudinal groove of substantial depth in the overlapping convolutions to secure them against sliding relative to each other in a direction tube. 4

2. A iexible tube comprising overlapping spirall wound convolutions, and a groove presse into the overlapped convolutions from the exterior of the tube providing coacting means on adjacent convolutions to hold them against relative sliding movement vin a direction longitudinally of the convolutions.

In testimony whereof 'I aflix my signature.

CHARLES S. HUNGERFORD.

.peripherally of the 

